<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        div{
            background: red;
            width: 200px;
            height: 100px;
            border-radius: 100px  100px 0 0  ;
        }
        div.a{
            background: #A9A9A9;
            width: 100px;
            height: 100px;
            border-radius: 50%;
        }
    </style>
</head>
<body>
<div></div>
<div class="a"></div>
</body>
</html>